Ive just noticed that my rear brake drums are getting very hot. With it being both of them I suspect the proportioning valve. Could this be right? It was heavily loaded last week but usually not much in it, could it be anything to do with it? Can I adjust it easily? Is it DIY job?
Thanks in advance.

It's unlikely to be the load valve, they do suffer with binding rear brake shoes though.
Strip the rear brakes down and rebuild using a white (calcium based) grease on all metal rubbing points.
Also check hand brake cable for smooth operation.
Should be OK then.
Chris

is it only hot with the load on or hot now you have no load on ?

There is hardly any weight in it and they still get hot. I've had experience of rear brake problems and have developed a habit of checking by slowly rolling to a standstill to see if it has a slight halt.

My back brakes seize up every 6 months or so and have to be released and greased

I had a good look last night and the two return springs for the handbrake were so encrusted they hardly worked. A lot of wriggling and greasing released them and handbrake adjusted. First journey=no hot drums, fingers crossed! There is a pivot protected by a rubber boot, assuming this is to stop debris etc. from interfering with the movement.

I have constant problems with my rear brakes siezing, but it doesnt help that a drive through water quite a lot.

I basikly take them apart and free up/grease any joining/rubbing parts.

The cylinders were also siezed last time so im replacing them also.